Method and apparatus for providing inductive coupling and decoupling of high-frequency, high-bandwidth data signals directly on and off of a high voltage power line

ABSTRACT

The present invention is drawn to an electrically “closed” method and apparatus for transmitting and receiving data signals over a high voltage power line. Inductive coupling is employed for coupling and decoupling the data signal directly on to and off of a single power line wire. An exemplary device includes a high frequency inductive coupling toroid for data signals, a second (50-60 Hz) inductive coupling toroid for providing power, signal conditioning electronics for the receive and transmit signal, a fiber optics interface for electrical isolation purposes, and a weather-proof enclosure. In a preferred embodiment, the toroids are hinged for ease of installation on a power line. A pair of such couplings on either side of a fiber-optic isolator can be used to bridge transformers.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. §119(e) fromprovisional application No. 60/268,578, filed Feb. 14, 2001. The60/268,578 provisional application is incorporated by reference herein,in its entirety, for all purposes.

FIELD OF THE INVENTION

[0002] The present invention is concerned with the field of transmittingand receiving high frequency, high bandwidth signals safely andefficiently over power lines. An exemplary system comprises a power linecoupler of the present invention, a fiber optic isolator and acommunications interface to various media. More specifically, thepresent invention is drawn to a method and apparatus for coupling to ahigh voltage power line for transmitting and receiving high frequency,high bandwidth signals.

BACKGROUND

[0003] With well-established power distribution systems (PDSs) alreadyin place throughout much of the world, an efficient power linecommunication system (PLCS) could provide more users with high-speedtelecommunications access with the minimum investment of “add-on”devices.

[0004] The infrastructure for providing broadband Internet access ispresently insufficient to meet demand. A power distribution system(PDS), however, could be an ideal vehicle for carrying communicationssignals in order to meet this demand. Development of a power linecommunication system (PLCS) would therefore provide more users withhigh-speed telecommunications access. Since the PDS is already built,the time required to implement a PLCS would be minimal.

[0005] Of course, there are a series of problems to be overcome before aPDS can be used as an efficient, high-speed power line communicationsmedium. The following issues, while not exhaustive, are representativeconsiderations of what such a system would require in order to use anexisting PDS to transport communication data: a sufficient signal tonoise ratio; non-disruptive installation of the “add on” device; safetymeans such that users and circuitry are protected and isolated fromstray current; a signal carrier with a frequency sufficient to supporthigh data transfer rate (e.g. 10 Mbps); means for the data signal tobypass a distribution transformer without loss; bidirectional datatransmission; coupling devices that do not interfere with data signalhandling; an independent power source for electronic conditioningcircuitry at power line interfaces; a power line interface that isimpervious to extreme environmental conditions; and means for the datato be readily routed to intended locations without loss.

[0006] Given the advantages of being able to use the existing PDS forhigh-speed data communication, an effective method is required to coupleand decouple the signals onto and off of a high or medium voltage powerline. The coupling and decoupling of the data signal must be at a levelsufficient to maintain an adequate signal to noise ratio in order todiscern between the data signal and noise or interference on the line.For any method developed, a significant challenge lies in being able tomitigate the adverse effects of the high voltage 50-60 Hz power signalmight have on the communications signal.

[0007] Whyte, et al. in U.S. Pat. No. 4,142,178 observe: “The use of thedistribution network conductors for the transmission of carriercommunication signals presents many problems not encountered in highvoltage transmission line communication systems. Some of these problemsinclude the poor high frequency impedance characteristics and the highlevel of electrical noise present on the distribution network conductorswhich, along with the plurality of distribution transformers and powerfactor correction capacitors attached to the distribution network,rapidly attenuate the communication signals.”

[0008] Whyte teaches using a direct circuitry from a line coupler to aremote data terminal thus bypassing the PDS transformer, which is theprimary source of data attenuation. The main use for the transmission ofcommunication signals addressed by Whyte was to perform distributionfunctions such as automatic reading of utility meters and selective loadcontrol. Those functions are still desirable, but the function of highspeed, high bandwidth communication transmission preclude directconnection from a transformer to remote data terminals economically.

[0009] Use of a low voltage power distribution system as a datacommunications carrier within a premises is well known. Abraham, U.S.Pat. No. 6,014,386 teaches a communications network within a buildingusing the AC wiring as the infrastructure of the network. Differenttypes of appliances using digital signals may be included within thenetwork. The Abraham patent uses an impedance matching scheme to directa specific signal to a specific location. Couplers at a control locationhave unique impedances that are matched by corresponding couplerselsewhere within the building. Thus, specific signals will be de-coupledbased an impedance match. Abraham also teaches the use of dielectricinductors in circuit with capacitors to tune the impedancecharacteristics of couplers.

[0010] In a similar manner, Abraham in U.S. Pat. No. 5,625,863 teachesthe distribution of multiple video signals distributed within a buildingusing the building's AC wiring as the distribution system. Uniqueimpedance settings direct the signals to unique locations. Abraham inU.S. Pat. No. 5,818,127 describes a distribution system for FM signalswithin a building by use of the building's AC wiring.

[0011] Abraham in U.S. Pat. No. 5,717,685 describes the coupling of datasignal on and off a building's AC wiring infrastructure. His inventionuses capacitive circuits in serial connection. The circuitry alsoincludes air-core transformers. This arrangement allows impedance tuningof the specific couplers. While Abraham claims a system with a fiberoptic source for an input signal in his U.S. Pat. No. 6,014,386, thereis no description as to the use of fiber optic isolators.

[0012] Abraham also states that the utility firm may use thecommunications system to communicate utility meter information over thePDS.

[0013] Methods for avoidance of distribution transformers are wellknown. Perkins in a series of patents including U.S. Pat. No. 4,473,816teaches a communications signal bypassing a multi-phase powertransformer where the signal uses the PDS as a carrier. The signal isbidirectional and uses conductive material to affect the bypass. Theinvention uses multiple capacitors in parallel to neutralize thecoupling impedance. Further, the winding ratio, R, between the primaryand secondary windings ratio is maintained in the signal frequencyacross the signal bypass. Signal carrier frequency is in the 3-10 KHzrange. Similarly, Perkins in U.S. Pat. No. 4,473,817 teaches acommunications signal bypassing a single-phase power transformer.

[0014] Kennon, U.S. Pat. No. 4,644,321 uses a non-intrusive coupler tocapture the data signal. Kennon teaches the use of a toroid having amultiplicity of turns of a conductor that is in circuit with anamplifier and receiver. The toroid core is non-conductive. The signalthus inductively de-coupled is amplified and used for a load managementand filed configuration utility terminal. The system requires a batteryfor circuitry management.

[0015] Brown, U.S. Pat. 5,949,327 teaches the use of transformer bypassby coupling using capacitors connected to the primary and secondaryterminals of the step transformer. Brown recognizes the need formultiple couplings at different points within the EDN (ElectricalDistribution Network or, as referred to in the present description asPDS). Brown also teaches that the communication system use a highfrequency signal carrier technique such as CDMA.

[0016] Moore, U.S. Pat. No. 5,210,519, describes a communication systemthat couples data signal from a transmission source using an inductorand de-couples the data at the receiver. This methodology is applied ina closed network and requires selective de-coupling as opposed torouting of the signal. Further, Moore teaches the use of a secondtransformer for reversing any inductor core saturation that may haveoccurred in the data de-coupling. This method requires time division ofthe data coupler between data coupling and saturation neutralization.

[0017] Dzung, European Patent Application EP948143, describes a highvoltage power line communication system that combines multiple sourcedata signals, couples the combined signal onto multiple power linesusing capacitive coupling and de-couples and demodulates the signals,separating and converting the signals back to the original form at thereceiver.

[0018] Power lines can be located in areas with extreme environmentalconditions. Thus, the mechanical design must ensure proper operationwhen exposed to these extreme conditions and also maintain the requiredlevel of safety. Furthermore, any methods developed should be designedso as to have minimal impact to service of customers duringinstallation.

[0019] Public safety is an absolute requirement. Any system using thePDS must isolate the end user (and public in general) from exposure toelectric current. The PDS steps medium and high voltage power down tolow voltage power (approximately in the 100-240 volt range) usingtransformers. Transformers are designed to filter out and ground highfrequency signals as a safety precaution. Since a high frequency signalcarrier is the ideal medium for high bandwidth data transfer, acommunications data delivery system needs to circumvent the transformerfiltration process while preserving safety protection.

SUMMARY OF THE INVENTION

[0020] It is an object of the present invention to provide a power linecoupler device for use with a power line communication system (PLCS).

[0021] It is another object of the present invention to provide a powerline coupler device for use with a high frequency signal carriersufficient to support high data transfer rates.

[0022] It is still another object of the present invention to provide apower line coupler device that operates under the various line voltageswithin the PDS.

[0023] It is yet another object of the present invention to provide apower line coupler device that enables electrical current isolation.

[0024] It is still a further object of the present invention to preservesignal to noise ratio for the communications signal.

[0025] It is yet a further object of the present invention to preservesignal to noise ratio for the communications signal bi-directionally.

[0026] It is another object of the present invention to provideinductive signal coupling in a PDS.

[0027] It is a further object of the present invention to provideinductive signal coupling in a PDS where the coupler's core remainsunsaturated.

[0028] It is a further object of the present invention to provide apower line coupler device that is non-intrusive.

[0029] It is still a further object of the present invention to providea power line coupler device that inductively draws operating power fromthe power line.

[0030] It is a further object of the present invention to provide apower line coupler device that is self-contained

[0031] It is a further object of the present invention to provide apower line coupler device that is self-contained and is nearlyimpervious to environmental conditions.

[0032] It is another object of the present invention to provide a powerline coupler device that uses a toroid inductor to inductively coupleand de-couple signals to and from a power line.

[0033] It is yet another object of the present invention to provide apower line coupler device that provides an electronic-to-lighttransducer to interface with a light conducting isolator.

[0034] It is still another object of the present invention to provide anon-intrusive power line coupler device with a hinged power line couplerfor ease of installation.

[0035] The PDS topology can be used to deliver high-speed communicationsto residential homes in a cost effective way. Applications for suchcommunication systems include high speed Internet, telephony, videoconferencing and video delivery. This recitation of applications is notmeant to be exhaustive.

[0036] The system involves coupling and de-coupling communications databetween a data source and a PDS. High frequency signals allow highbandwidth transfers (the higher the frequency of the data carrier, themore cycles per unit time available for data transfer). The signalcarrier should exhibit high signal to noise characteristics relative tothe underlying system of a 50 or 60 Hz PDS. (The US standard is 60 Hz,but most countries use a 50 cycle per second power system.)

[0037] The data signals are coupled on to and off of the power line witha power line coupler (PLC) device. One embodiment of the presentinvention uses an inductive method to couple and de-couple data signalsoff of the power line. A toroid with conductive windings is placedaround the power line. This method effectively provides a transformerbetween the power line and the PLC device circuitry thus facilitatingthe transmission and receiving of the data signal. For the primary sideof the transformer, the number of windings and the orientation of thewindings around the magnetic toroid is guided by the desire to maximizethe flux linkage.

[0038] The type of signal used on this channel can be almost any signalused in communications (CDMA, TDMA, FDM, OFDM to name a few). A widebandsignal such as CDMA that is relatively flat in the spectral domain ispreferred to minimize radiated interference to other systems whiledelivering high data rates.

[0039] Since communications signals are very high frequency, a step downtransformer would filter a signal coupled on the power line. The systemto which present invention is a component avoids filtering of highfrequency signals by bypassing the transformer with a power line bridge(PLB). The PLB, using a PLC device, de-couples data signals from themedium (MV) or high voltage (HV) line a short distance from atransformer. The PLB interfaces between the power line on the primary ofthe transformer and the low voltage (LV) line on the secondary of thetransformer. (The primary is the side of the transformer where therelatively high voltage enters; the secondary is the side of thetransformer where the stepped down, lower voltage exits thetransformer.)

[0040] The PLB is used to prevent the relatively high voltage frompassing to the transformer's secondary side yet allowing thecommunications signal to pass between the PDS on either side of thetransformer. The bypass is accomplished with the use of an isolator. ThePLC device includes circuitry to interface with an isolator. A preferredembodiment of the system of which the present invention is a componentis to use an optical medium as an isolator.

[0041] The de-coupled signal from the relatively high voltage power lineis converted to light energy (i.e. light signal) by using a transducerand transmitting the light signal over a non-electrically conductive butlight conductive medium.

[0042] A preferred embodiment of the present system uses a fiber opticcable as the isolator. The isolator is a light pipe that bypasses thetransformer. Fiber optic cable is a dielectric thus insulating the PDSon the secondary transformer side from relatively high voltage.

[0043] As described in a companion application by the present inventor,application Ser. No. 09/835,532 filed Apr. 16, 2001, the signal is nextmodulated and demodulated by a first modem. The signal goes through adata router and then a second modem. The router serves the purpose ofmatching data packets with specific messages and destinations. Thesecond modem modulates and demodulates the signal in a form consistentwith transport over a LV power line.

[0044] The light signal is converted back to an electronic signal andthen coupled onto the LV power line (LV coupler). In an embodiment ofthe present invention a second isolator is inserted in the systembetween the second modem and the data router for conversion of the lightsignal to electrical signal. Additionally the isolator proves anadditional layer of safety because of the dielectric quality of thesecond isolator.

[0045] The high speed, high frequency signal is then delivered, over theLV power line to the end user's residence or place of business. A powerline interface device (PLID) serves as the gateway between the enduser's various data appliances and local area network (LAN) and the highspeed data transport.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 discloses the typical electric distribution topology of theprior art.

[0047]FIG. 2 illustrates typical electric distribution topology modifiedfor communication in accordance with the present invention.

[0048]FIG. 3 illustrates a block diagram of the AP in accordance withthe present invention.

[0049]FIG. 4 illustrates a block diagram of the PLB in accordance withthe present invention.

[0050]FIG. 5 illustrates a conceptual diagram of a power line couplingin accordance with one embodiment of the present invention.

[0051]FIG. 6 illustrates a diagram of a self-contained power linecoupling in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0052] The present invention is a power line coupler device speciallysuited for coupling and de-coupling high frequency, broadband signalscarried over power lines within a power distribution system. The PLCdevice includes the coupler and circuitry necessary to condition thesignal, to handle bi-directional signal transfer, to enable the use ofan isolator, to be self-contained and to be able to provide operationalpower from the power line. The PLC device is part of an overall powerline communication system (PLCS) which incorporates the presentinvention and other, companion inventions from the same inventor. Thefollowing description is a description of the PLCS in general. The PLCdevice embodiment is included in the system description. The descriptionpertinent to the PLC device should be apparent to one skilled in theart.

[0053] Referring to FIG. 1, the typical electric distribution topologyof the prior art is illustrated. Medium voltage (MV) half loop powerdelivery system, as illustrated, is common to the US PDS. Manytransformers are used. Each transformer services a few homes or smallbusinesses. Many other countries, such as the European states, use ahigh voltage delivery system with many end users serviced from atransformer. The present invention is applicable to either environment.

[0054] The power line communication system may be implemented in a highvoltage and medium voltage environment (i.e. 1-100 kVAC). For purposesof this description and claims, the high and medium voltage portion ofthe PDS is described as primary voltage (PV). The low voltage portion ofthe system is described secondary voltage (SV). These terms arearbitrary but used to improve clarity of the description. Similarly, theside of a transfer where the PV line enters is called the “primary”side. The SV side of the transformer is referred to as the “secondary”side of the transformer.

[0055] A sub-station 10 delivers PV power to a half loop distributionpoint, pole dip 12. The power is delivered in parallel to multipletransformers 20 over a PV power line 14. After the transformer isstepped down to a SV power (in the range of 100 to 240 VAC), several enduser premises 26 are serviced via a SV power line 24. The step downtransformer 20 grounds high frequency signals for safety purposes. Sincea high data transfer (high bandwidth) power line communication deliverysystem requires a high frequency signal carrier, an object of thepresent invention is to avoid the removal of the high frequency signalby the transformer 20. It is noted that the PV power lines 14 may beabove ground or subterranean. The transformers 20 may be aerial mountedon a pole or pad mounted on the ground.

[0056]FIG. 2 illustrates the typical electric distribution topology asshown in FIG. 1 as modified for communication in accordance with thepresent system. A point of presence 40 (POP), the gateway for highfrequency, high bandwidth data signal, provides communications withdigital providers. It both sends and receives data to the end user overthe PDS. A backhaul link 42 connects the POP 40. Data is manipulated andcoupled and de-coupled from the PV power line at an aggregation point 44(AP). A more detailed description of the AP follows in the FIG. 3discussion.

[0057] The PDS is viewed as having three channels: PV power line; SVpower line; and the premise's wiring. The first channel (the PV cable)has the least amount of noise and least amount of reflections. Thischannel has the highest potential bandwidth for communications. This isimportant because it is the channel that concentrates all of thebandwidth from the other channels. The type of signal used on thischannel can be almost any signal used in communications (CDMA, TDMA,FDM, OFDM to name a few). A wideband signal such as CDMA that isrelatively flat in the spectral domain is preferred to minimize radiatedinterference to other systems while delivering high data rates

[0058] The second channel (SV line from the transformer to the premise)and third channel (premise wiring) have noise present from electricalappliances and reflections due to the “web” of wires. These channelssupport a lower bandwidth than the PV channel and they need a moreintelligent (with more overhead) modulation scheme. There are severalcompanies with chip sets to achieve good communications for local areanetworks (LANs) such as: Adaptive Networks (Newton, Mass.), Inari(Draper, Utah), Intellion (Ocala, Fla.), DS2 (Valencia, Spain) and Itran(Beer-Sheva, Israel). These devices would work well for the SV andpremise channels.

[0059] Data signal and power are carried over the PV power line 14 aspreviously stated. A power line bridge 46 (PLB) allows the data signalto bypass the transformer 20 thus avoiding the grounding of the highfrequency data signal. More description of the PLB follows in the FIG. 4description. The data signal after manipulation is delivered to the enduser's premise. The data signal enters premise via the SV wiring. Theend user may have a local area network (LAN) or have individual digitalappliances.

[0060] In one embodiment of the present system, the signal is carriedthrough the premise's wiring 24 and is available to various digitalappliances 29, 30, including PC's, by a power line interface device 28(PLID). The PLID 28 plugs into a standard electrical socket and allowsthe digital appliance to send and receive digital data. An alternativeembodiment as described later, uses a communications interface locatedoutside of the premise and the data signal is directly fed to thepremise.

[0061] Referring next to FIG. 3, a block diagram of the AP 44 inaccordance with the present invention is illustrated. The AP 44 is thepoint where digital data is coupled and de-coupled to the PV power line.Additionally, the data is processed so that it can be readilycommunicated. Data signal communication to and from POP 40 is providedby the backhaul link 42.

[0062] A backhaul interface 50 allows direct communication with POP 40.The signal is passed through a high or medium voltage signal modem 52(PV modem). An isolator 54 is used to prevent electric current fromflowing between the PDS and the components leading to the POP 40. Theisolator 54 is made from dielectric material. The isolator, in apreferred embodiment of the present system, is a fiber optic light pipe.More description of the isolator and its components occurs in thedescription referring to FIG. 6.

[0063] The isolator 54 bridges between the PV modem 52 and a power linecoupler 56. The PV modem 52 within the AP 44 conditions the signal fortransmission over the PV power line 14. When data is transmitted by theend user and is de-coupled off of the PV power line, the PV modem 52conditions the signal for transmission back to the POP 40.

[0064] In one embodiment of the present system, the power line coupler56 comprises, along with other components, an inductor having a toroid(donut-like) shaped core. The toroid core has permeability qualities toimprove signal to noise ratio. More description of a preferredembodiment for the power line coupler is presented below. The inductorcouples and de-couples a high frequency signal to and from the powerline without invading the power line. Once the data signal has beencoupled to the PV power line, it is transported on the PV power line 14.

[0065] Referring to FIG. 4, a block diagram of the PLB in accordancewith the present system is illustrated. The PLB 46 bypasses thetransformer 20 linking the data signal between the PV power line and theSV power line. At either end of the PLB 46 is a coupler. A PV coupler 60couples and de-couples signal with a PV power line 14. A SV coupler 72couples and de-couples signal with a SV power line 24.

[0066] An isolator is present between the PLB end couplers 60,72 and theinterior of the PLB 46. The isolators, a PV isolator 62 and a SVisolator 70, are composed of dielectric material and insulate thebalance of the PLB from potential electrical damage and user injury. Apreferred embodiment of the isolator uses fiber optic material. Theisolator is discussed in more detail below.

[0067] A PV modem 64 modulates and de-modulates the signal to and fromthe PV isolator. The PV modem conditions the high frequency signals fortransmission over the PV power line 14. The SV modem 68 conditions thesignal for communication over a SV power line. In one embodiment of thepresent invention, a data router 66 is between the SV modem 68 and thePV modem 64. The function of the data router 66 is to prioritize andgather packets from all of the devices on SV power line side PV powerline side. The data router 66 provides data packet management of enduser transmission.

[0068] The signal (going to the end user) is coupled onto the SV powerline by the SV coupler 72. The SV power line 24 delivers the powerservice to an end user premise 26. A “web” of wires distributes powerand signal within the premise. The user draws power on demand byplugging an appliance into a power outlet. In a similar manner, the usermay use a power line interface device 28 (PLID) to digitally connectdata appliances, receiving and sending data signals carried by the powerwiring.

[0069] A PLID 28 can have a variety of interfaces to the subscriber'sequipment 30, 32. Some examples are RJ-11 Plain Old Telephone Service(POTS), RS-232, USB, and 10 Base-T. A subscriber can have more than oneinterface device 28 on the same premise wiring.

[0070] Referring to FIG. 5, a conceptual diagram of a power line couplerdevice in accordance with one embodiment of the present invention isillustrated. The description of the system includes a PLB 46. Theembodiment conceptualized in FIG. 5 replaces the PLB 46 with aself-contained power line coupler device 100, a fiber optic isolator 130and a communications interface 140. Further, the transformer 20 isdepicted as pole mounted. The Communications Interface 140 separatessignal carried over the PV power line 14 into three components: SV powerline 24; wireless link 150; and telephone line 160, although this is notmeant as a limitation.

[0071] Referring to FIG. 6, a diagram of a self-contained power linecoupler device in accordance with one embodiment of the present systemis illustrated. The self-contained power line coupler device is packagedin a weatherproof housing 102 to militate against harsh weather andenvironment conditions. The PV power line 14 passes through openings inthe container. A data signal coupler 104 couples and de-couples datasignals transported by the PV power line 14. One embodiment of thepresent invention uses a magnetic toroid shaped inductor. Windings 108are placed around the inductor 104 to facilitate flux linkage of thedata signal. The number of windings and the winding orientation isselected to maximize flux linkage. The permeability of the magnetic coreis chosen for maximum coupling with the high frequency data signal. Corepermeability characteristics prevent low frequency power line signalsaturation of the toroid core. If the inductor coupler 104 becomessaturated with low frequency signal, the coupler would lose its abilityto couple or de-couple high frequency signal. Low frequency, as used inthis description and claims, are frequencies in the range of 1-100 Hz,typically 50-60 Hz.

[0072] The toroid 104 has direct electrical connection to the signalconditioning electronics used for transmitting and receiving the datasignal. Transmit and receive circuitry 110 carries data signal to signalconditioning electronic components. As depicted in FIG. 6, the transmitcircuitry 112 and the receive circuitry 114 are in parallel. Anotherembodiment of the present invention uses two data signal couplingtoroids. One coupler is used for receiving and one for transmitting inorder to optimize the flux linkage for the two cases. (FIG. 6, however,depicts only a single signal coupler.)

[0073] The design of the transmit side is done to maximize the power ofthe drive signal in order to keep the signal to noise ratio of thecoupled signal at least to the level acceptable for the overallcommunications system. The receive side contains a low noise amplifierdesigned to handle the lowest acceptable transmit signal level of thesystem. At a system level, the modulation and signaling scheme is doneto minimize interference between transmit and receive signals.

[0074] The signal conditioning circuitry communicates with the fiberoptics interface via an electronic/light transducer 116. Laser diodesmay be used to implement a light transducer. The transducer convertselectrical signal to light signal in the receive circuitry 114. Thetransducer converts light signals to electrical signals in the transmitcircuitry 112. The light signal is transmitted to and from a light pipe130 (fiber optic cable). The data signals are communicated back andforth between the power line coupler 100 and the CommunicationsInterface 140 via a fiber optic cable 130. The Fiber Optic Isolatorbreaks any electrical path between the two devices thus providing safetyfor the system.

[0075] With the power line coupler device being a “closed” system, powerfor the electronics must be derived internally. Batteries may be anoption but replacement would be costly and impractical. In oneembodiment of the power line coupler device, a power draw toroid 106 isprovided. The power draw toroid 106 has magnetic characteristicsappropriate for coupling low frequency signals, thus inductively drawingsome of the power off of the power line and providing a power supply 118for the power line coupler device.

[0076] For additional safety, the power line couple device externalshell or housing 102 is constructed from dielectric, corrosiveresistant, weatherproof materials and is designed to significantlyreduce any possible exposure to the high voltage potential present onthe power line. The Fiber Optic Isolator 130 is the only connectionbetween the power line coupler device 100 and the communicationsinterface 140. Further, the light pipe is encased in the insulatedhousing 102. The first priority of the housing 102 is to protect fromexposure to the high voltage potential. It is also designed to ensureproper operation under extreme environmental conditions. The externalshell is assembled using fasteners including adhesives. The assembledshell is sealed with a dielectric, weatherproof sealant around anyseams, fasteners, and power line and conduit openings. Sealing enhancesthe weatherproofing.

[0077] In another embodiment of the present invention, a “hinged” toroiddesign allows for easy installation and minimal impact to customerservice. The toroids, one or two coupling toroids and a power supplytoroid, simply snap around the power line using existing utility toolsand techniques.

[0078] The communications interface 140 communicates with the power linecoupling device 100 via the fiber optic isolator 130. Received signalsare separated into digital data signals and any other communicationsignal that may be carried by the PV power line. FIG. 5 depicts threetypes of leads from the communications interface: 120/240 V power line24 (SV power line); wireless link 150; and telephone link 160. The SVpower line receives current from the transformer 24. The digital datasignal is coupled on and off the SV power line 24 within thecommunications interface.

[0079] The description of one embodiment of the present system includinga PLB 46 for providing a means for converting light signals to coupleddigital data signals as delivered to a premise over SV power line hasbeen made. The communications interface implements the coupling andde-coupling of digital data signal on and off the SV power line in asimilar fashion.

[0080] A system as disclosed herein is useful to provide data servicesto the residential market place at 10 Mbps. This makes an entire newrange of applications practically available. Each device connected tothe PLID would (if desired) have an address and would be accessibleremotely. Some examples include broadband Internet access, remoteutility meter reading, Internet Protocol (IP)-based stereo systems,IP-based video delivery systems, and IP telephony.

[0081] The present system and the present invention have been describedin terms of preferred embodiments. However, it will be appreciated thatvarious modifications and improvements may be made to the describedembodiments without departing from the scope of the invention.

What is claimed is: 1] A method for transmitting and receivinghigh-frequency data signals over power transmission lines, comprising:coupling and un-coupling high-frequency electrical data signals with afirst power transmission line by inductance; conditioning said coupledand un-coupled high-frequency electrical data signals; and coupling andun-coupling high-frequency electrical data signals to a first end of afiber-optic isolator using a light transducer and a light pipe. 2] Themethod of claim [c1], further comprising providing said inductance bypositioning said first power transmission line inside a toroid shapedcore having a plurality of windings. 3] The method of claim [c2],further comprising preventing low frequency power line signal saturationof said core by forming said core with a magnetic material of sufficientpermeability. 4] The method of claim [c2], further comprising formingsaid core as two portions with a hinge therebetween to easeinstallation. 5] The method of claim [c1], further comprisinginductively providing power for said conditioning and said lighttransducer using a second toroid surrounding said first powertransmission line and including a sufficient number of windings toinductively transfer desired power. 6] The method of claim [c5], furthercomprising forming said second toroid as two portions and joining saidportions together with a hinge. 7] The method of claim [c1] furthercomprising coupling said fiber-optic isolator to an interface device forelectronic data signal devices. 8] The method of claim [cl], furthercomprising: coupling and un-coupling light signals from a second end ofsaid fiber-optic isolator using a second light pipe and a second lighttransducer for high-frequency electrical data signals; conditioning saidcoupled and un-coupled high-frequency electrical data signals; andcoupling and un-coupling high-frequency electrical data signals with asecond power transmission line by inductance. 9] The method of claim[c8], further comprising providing a second inductive power source forat least said second light transducer. 10] The method of claim [c1],further comprising providing said coupling, un-coupling and conditioningsteps within a protected environment. 11] A device for transmitting andreceiving high-frequency data signals over power transmission lines,comprising: an inductor adjacent to a first power transmission line;signal conditioning circuitry electrically connected to said inductor; alight transducer electrically connected to said signal conditioningcircuitry; a light pipe adjacent to said light transducer; a fiber-opticisolator connected to said light pipe; and a power source for saidsignal conditioning circuitry and said light transducer. 12] The deviceof claim [c11] wherein said inductor comprises a toroid shaped corehaving a plurality of windings and said inductor is positioned such thatsaid first power transmission line runs through a center of said core.13] The device of claim [c12] wherein said core comprises a magneticmaterial of sufficient permeability to prevent low frequency power linesignal saturation of said core. 14] The device of claim [c12] whereinsaid toroid shaped core comprises two portions joined together with ahinge. 15] The device of claim [c11] wherein said power source comprisesa second toroid surrounding said first power transmission line andincluding a sufficient number of windings to inductively transferdesired power. 16] The device of claim [c15] wherein said second toroidcomprises two portions joined together with a hinge. 17] The device ofclaim [c11], further comprising an interface device coupled to saidfiber-optic isolator, said interface device including means to interfacewith digital appliances. 18] The device of claim [c11], furthercomprising: a second light pipe adjacent to an opposite end of saidfiber-optic isolator; a second light transducer connected to said secondlight pipe and electrically connected to a second set of signalconditioning circuitry; said second set of signal conditioning circuitryelectrically connected to a second inductor; and said second inductoradjacent to a second power transmission line. 19] The device of claim[c18], further comprising a second power source for said second set ofsignal conditioning circuitry and said second light transducer. 20] Thedevice of claim [c11], further comprising a weather-proof enclosure forat least said inductor, said signal conditioning circuitry, said a lighttransducer, and said light pipe.